1. Field of the Invention
This invention relates to the prevention of fouling of substrates in water environments, such as marine or fresh water environments, and particularly to the prevention of fouling coupled with corrosion inhibition by the application of a coating of technetium-99 to the substrate.
2. Description of the Prior Art
Marine and fresh water organisms, e.g., algae, sea worms, sea plants, barnacles, crustacea, etc., cause millions of dollars of damage each year to underwater substrates, such as ship hulls, instrument transducers, condensers, heat exchangers, underwater instrumentation such as seawater gauges, current meters, temperature sensors, pressure sensors, salinity sensors, underwater television, liquid level gauges, water meters, underwater navigation equipment, and the like; buoys, not only including navigation buoys, but also instrumentation mooring packages, mooring buoys, locator buoys, environmental data buoys, and the like; flotation equipment such as flotation packages for instrumentation, flotation equipment for underwater salvage work and the like; water pumps, both fixed and submersible; metal piling connectors, such as bolts, pins, and the like; offshore drilling equipment such as tool joints, subs and connectors, drill collars, floating guide shoes, casing and tubing heads and supports, substructures and accessories; water intake and exhaust screens and screen wells; interior surfaces of water storage tanks; desalination equipment, particularly those portions of the system which carry the high salt content overflow (an area of particularly high corrosion problems); submarine ballast tanks, underwater sonar equipment, cooling towers, and, in general, any surface in contact with water, by forming growths of the organisms on the surface of these in-the-water devices. Eventually there results undesirable and damaging fouling which, at the least, is very expensive and time consuming to remove, or may totally destroy the usefulness of the device whose surface is affected.
The prior art has developed numerous anti-fouling paints for application to in-the-water devices, particularly ship hulls. However, these anti-fouling paints eventually peel off from the surface during use and therefore only have a limited life expectancy requiring frequent costly shutdowns and reapplications. Particularly in the case of stainless steel devices, adhesion of the anti-fouling paints is unsatisfactory. Also, anti-fouling paints unless applied in relatively thick coatings are subject to small cracks which expose the surface of the coated device and allow penetration by corrosive salt water and/or the above-mentioned organisms. Even very minute cracks in the paint can result in damage to the coated device. Anti-fouling paints have the additional disadvantage in that the paint can easily be scratched or scraped off of the surface. Also, anti-fouling paints too frequently create a health hazard to non-harmful sea life because of the nature of the poisonous substances in the paint. Fouling and corrosion prevention is particularly important for underwater instrumentation having moving parts, such as transducers of the flexible diaphragm type, or liquid level measuring devices utilizing a sliding rod. Such devices become totally ineffective when fouled by marine or fresh water organism growth.
The problem of keeping underwater instrument transducers and other underwater instrumentation, etc., free of marine fouling has heretofore remained unsolved.